Curtain walls protect the outer walls of buildings from weather effects such as thermal expansion and air and water infiltration.

Curtain wall systems often form an insulated glass unit with aluminium or steel frames, allowing natural light through to the building interior.

They are popular additions to high rise buildings, providing an air barrier, thermal breaks and rigid insulation to these vulnerable structures.

Yet, there are common misconceptions surrounding these robust systems. The following article will explore curtain walls in more detail.


What is a curtain walling system?

A curtain wall system is an outer covering of a building that is formed from a metal frame (mullion) containing infills of a lightweight material, such as glass, metal panels, or thin stone.

Curtain walling is used to enhance appearance and protect the building from weather. From an architectural perspective, a curtain wall can help to separate the interior from the exterior.

Insulating glass in-fills can increase the amount of natural light that enters the building. Glazed curtain walls – using solar control, transparent, translucent or opaque glass – prevent the curtain walling from creating a greenhouse effect.

Curtain wall construction is designed to resist air and water infiltration; sway induced by wind; seismic forces acting on the building; and their own dead-load weight forces.

Traditionally curtain walls are most suited to the façades of large multi-storey buildings and can be seen on famous structures across the world; for example, London’s Gherkin and the Empire State Building in New York.

Developments in thinner, aluminium frames have made curtain walling systems easily applicable to buildings of any size. Both horizontal and vertical curtain walling is available, both of which can be applied to domestic and commercial properties.

Curtain wall systems are easy to install, easy to transport and simple to manufacture. The use of lightweight materials minimises construction costs and each curtain wall can be custom-made to suit your unique project.

Off-the-shelf proprietary curtain wall systems from manufacturers’ standard catalogues become cost competitive as the wall area increases.


Is curtain walling structural?

Curtain walling is non-structural, meaning that it is not an integral aspect of a building’s primary structure. Curtain wall systems are self-supporting, only carrying their own weight.

The curtain wall framing is attached to the building structure, but it does not carry the floor or roof loads of the building or support any structural elements.

The wind and gravity loads of the curtain wall may be transferred to the building, typically at the floor line.


What is the difference between cladding and curtain walling?

While cladding and curtain walling are both exterior walls designed to protect and enhance the appearance of a building’s façade, there are differences between the two:

  • Cladding is structural, while curtain walling is not
  • Cladding can be made from a greater variety of materials, including wood, metal, concrete, and reinforced PVCu
  • Cladding is easier to install, requires less maintenance and only periodic cleaning
  • Curtain walling is safer, since is completely self-supporting and does not put any additional load on the building’s structure
  • Curtain wall systems have a longer typical service life and provide greater weather protection, as well as greater thermal and acoustic insulation


Visually Attractive Facades

Curtain wall systems can be adapted to suit any building, offering a great variety of choices, from curved facades and geometrically shaped windows to multi-coloured powder-coating.

Aluminium is the most popular material for curtain wall frames due to its versatility and malleability. Anodized aluminum frames can be moulded into innovative shapes and sizes to suit any specific project.

High rise buildings with external walls that are vulnerable to the elements may benefit more from a curtain wall, but this method of outer covering can be stylishly applied to every building type.


Benefits of Curtain Wall Systems

  • Modern, state-of-the-art aesthetics and technical performance
  • Protection against water and wind penetration
  • Protection against building sway, as well as thermal expansion and contraction
  • Protection against fire and combustion gases
  • Reduction of solar transmissions; thermal efficiency
  • Energy efficient, helping to reduce heating, cooling, and lighting costs
  • Acoustic insulation
  • Cost effective due to lightweight materials
  • Easy to install, transport and manufacture
  • Self-supporting; less stress on the building structure and foundation
  • Adaptable to any building type


Types of Curtain Walling

Types of Curtain Walling System

There are two basic categories of curtain wall system that are based on the method of fabrication and installation:

Stick system – stick systems require the curtain wall mullion to be installed piece by piece on-site. The glazing panels are inserted from either the inside or outside. These frames provide lateral resistance while allowing for thermal movement.

Modular or unitized curtain wall system – these systems are composed of large, prefabricated units that are assembled and glazed in the factory and delivered to sites in sections before being erected on the building. These systems have a lower installation time.

Curtain wall technology can be designed to handle atmospheric moisture in different ways, using methods of sealing, draining and pressure equalising.


Types of Curtain Wall Infill Panels

Infills, or spandrels, are large panels that fit into the curtain wall frame.

Panels consisting of vision glass are the most popular, allowing natural light through to the interior. The type, thickness and glazing of the glass will be selected based on the project’s individual requirements.

Other building components for infills include:

  • Metal sheet, e.g. aluminum plate or steel
  • Stone
  • Brick
  • Terracotta
  • Louvers/vents
  • Fibre-reinforced plastic (FRP)

To find out more about curtain walling from an independent third party agency, contact Hive Architectural online or on 0161 339 9375.